Robust multifilament arrays in air by Dammann grating.

We compare transverse structure evolution and energy deposition into the medium within focused multifilament arrays created using two different types of diffraction optical elements (DOEs): TEM11 phase plate and a Dammann grating. We show that the employment of the Dammann grating provides a robust way to create regular multifilament arrays, which is far less dependent on laser beam quality than one using the phase plate.

Postfilament supercontinuum on 100 m path in air.

Pulses at 744 nm with 90 fs duration, 6 mJ energy, and a weakly divergent wavefront propagate for more than 100 m and generate a filament followed by an unprecedently long high intensity (≥1TW/cm2) light channel. Over a 20 m long sub-section of this channel, the pulse energy is transferred continuously to the infrared wing, forming spectral humps that extend up to 850 nm. From 3D+time carrier-resolved simulations of 100 m pulse propagation, we show that spectral humps indicate the formation of a train of femtosecond pulses appearing at a predictable position in the propagation path.

Hybrid stimulated Raman scattering-two-plasmon decay instability and 3/2 harmonic in steep-gradient femtosecond plasmas.

We numerically study interaction of a very intense (I∼10^{17} to 5×10^{19}W/cm^{2}) femtosecond obliquely incident p-polarized laser pulse with a steep-gradient (L∼λ) plasma, i.e., within the conditions typical for modern experiments. It is shown that the hybrid stimulated Raman scattering-two-plasmon decay instability develops near the quarter-critical density surface and plays the dominant role for the plasma waves' excitation and energy absorption. The plasmons are excited as two wave packets confined near this surface with very wide ≈ω_{0}/c spatial spectra along its normal. Hence, phase-matching conditions for the 3/2 harmonic generation are fulfilled immediately and include the mechanism coming from the high harmonics of plasma waves. This mechanism has been proved experimentally by observing an additional 3/2 harmonic beam.

Observation of crossover from intraband to interband nonlinear terahertz optics.

In this Letter, we investigate the nonlinear effects of extremely intense few-cycle terahertz (THz) pulses (generated from the organic crystal 4-NN, NN-dimethylamino-4'4'-N'N'-methyl-stilbazolium 2, 4, 6 trimethylbenzenesulfonate, with peak electrical fields of a few MV/cm) on the carrier dynamics in n-doped semiconductor thin film In0.53Ga0.47As. By performing open-aperture Z-scan measurements and recording the transmitted THz energy through semiconductor sample, we observed a strong THz absorption bleaching effect at high fields, followed by an absorption enhancement at even higher fields. We attribute our observations to a crossover from pure intraband carrier dynamics to an interplay between intraband carrier heating and interband carrier generations.

Ring and unimodal angular-frequency distribution of THz emission from two-color femtosecond plasma spark.

We study angular and frequency-angular distributions of the terahertz (THz) emission of the low-frequency region (0.3-3 THz) from a two-color femtosecond plasma spark experimentally and in three-dimensional numerical simulations. We investigate the dependence of the angular shapes of the THz radiation on focusing conditions and pulse durations by using two laser facilities (pulse durations 35 and 150 fs) for different focusing geometries. Our experiments and simulations show that decrease in the numerical aperture from NA ≈0.2 to NA ≈0.02 results simultaneously in (I) squeezing of the THz angular distribution and (II) formation of the bright conical emission in the THz range. The moderate focusing NA ≈0.05, which forms the relatively narrow unimodal THz angular distribution, is identified as optimal in terms of angular divergence. Numerical simulations with carrier wave resolved show that bright THz ring structures appear at the frequencies ≥2 THz for longer focuses (NA ≈0.02), while for optimal focusing conditions NA ≈0.05 the conical emission develops at THz frequencies higher than 10 THz.

Polarization control of terahertz radiation from two-color femtosecond gas breakdown plasma.

We individually control polarizations of 800 and 400 nm beams, which form a two-color femtosecond plasma filament in air irradiating a linear-to-elliptical THz signal. We detected a threshold-like appearance of THz ellipticity at the angle of ∼85° between the fundamental and second-harmonic field polarization directions. The simulations confirm the abrupt change of THz polarization and reveal that the weak ellipticity of the second harmonic is sufficient to generate essentially elliptical THz radiation.

Symmetry Breaking and Strong Persistent Plasma Currents via Resonant Destabilization of Atoms.

The ionization rate of an atom in a strong optical field can be resonantly enhanced by the presence of long-living atomic levels (so-called Freeman resonances). This process is most prominent in the multiphoton ionization regime, meaning that the ionization event takes many optical cycles. Nevertheless, here, we show that these resonances can lead to rapid subcycle-scale plasma buildup at the resonant values of the intensity in the pump pulse. The fast buildup can break the cycle-to-cycle symmetry of the ionization process, resulting in the generation of persistent macroscopic plasma currents which remain after the end of the pulse. This, in turn, gives rise to a broadband radiation of unusual spectral structure, forming a comb from terahertz to visible. This radiation contains fingerprints of the attosecond electron dynamics in Rydberg states during ionization.

Giant self-induced transparency of intense few-cycle terahertz pulses in n-doped silicon.

The results of high-field terahertz transmission experiments on n-doped silicon (carrier concentration of 8.7×1016 cm-3) are presented. We use terahertz pulses with electric field strengths up to 3.1 MV cm-1 and a pulse duration of 700 fs. A huge transmittance enhancement of ∼90 times is observed with increasing of the terahertz electric field strengths within the range of 1.5-3.1 MV cm-1.

Fifteen meter long uninterrupted filaments from sub-terawatt ultraviolet pulse in air.

A technique is presented to create uninterrupted long ultraviolet filaments in air using appropriately structured transmission mesh. The mesh with different cell sizes was inserted into 10-cm parallel beam of 0.2-J, 248-nm, and 870-fs pulse propagating along ~100-m corridor. Transverse positions of multiple filaments formed by the optimum size cells were reproducible within at least 15 m along the propagation path. 3D+time simulations confirmed uninterrupted plasma channels with fixed positions in the transverse space similar to the experiment. Unoptimized cell size resulted in filaments shifting towards the cell center and destruction of uninterrupted filaments.

An improved model of homogeneous nucleation for high supersaturation conditions: aluminum vapor.

A novel model of stationary nucleation, treating the thermodynamic functions of small clusters, has been built. The model is validated against the experimental data on the nucleation rate of water vapor obtained in a broad range of supersaturation values (S = 10-120), and, at high supersaturation values, it reproduces the experimental data much better than the traditional classical nucleation model. A comprehensive analysis of the nucleation of aluminum vapor with the usage of developed stationary and non-stationary nucleation models has been performed. It has been shown that, at some value of supersaturation, there exists a double potential nucleation barrier. It has been revealed that the existence of this barrier notably delayed the establishment of a stationary distribution of subcritical clusters. It has also been demonstrated that the non-stationary model of the present work and the model of liquid-droplet approximation predict different values of nucleation delay time, τs. In doing so, the liquid-droplet model can underestimate notably (by more than an order of magnitude) the value of τs.

[Relapsing polychondritis].

Relapsing polychondritis (RP) is a systemic inflammatory condition leading to irreversible structural changes in cartilaginous tissue as a result of generalized proteoglycane decomposition. Auricular and nasal cartilage is usually the first to be affected at the onset of the disease which leads to episcleritis. At the later stages, the larynx and trachea become involved, vasculitis develops affecting the organs of hearing, coronary arteries, kidneys, meninges, and other organs. The disease has an intermittent, recurrent character. The clinical course of RP is irregular. The disease is a rare occurrence and difficult to diagnose. The present review is based on the publications by domestic and foreign authors. It is intended to enhance awareness of the clinical picture and peculiarities of RP among clinicians with a view to improving its diagnostics.

[Pace of pulmonary function deterioration in patients with occupational bronchial diseases: influence of various factors].

Prospective cohort study covered 348 workers of dust-related occupations with verified occupational bronchial diseases. The authors studied dependence between industrial aerosol levels at workplace, smoking status and pace of pulmonary function decrease in individuals with chronic bronchitis and COLD. Conclusion is that totality of occupational bronchial diseases patients is uneven and differs in course and clinical and functional parameters.

[Characteristics of rat ceruloplasmin from the serum of animals, which received salts of silver with food].

Abiogenic Ag(I) ions have electronic structure, similar to Cu(I) ions and can compete with Cu(I) for binding sites of proteins which transport copper from extracellular media to sites of cuproenzyme formation in the cell. Rodents receiving Ag-salts with food develop extracellular deficiency of copper associated with ceruloplasmin (Cp, the major copper-transporting protein in blood serum of vertebrates). The present work focuses on the studies of biochemical and physicochemical properties of Cp, obtained from blood serum of rats, which received AgCl with food for 4 weeks (Ag-rats). Cp-fractions from blood serum of Ag-rats (Ag-Cp) were obtained by ion-exchange chromatography with stepped gradient of NaCl. Each fraction was tested for oxidase and ferroxidase activities by direct measurement of catalytic activity in the gel, and for specific activity in holo-Cp in oxidation of chromogenic substrate. Molecular mass, electrophoretic mobility and ratio of apo- and holo-forms in Ag-Cp fractions were evaluated by immunoblotting. Ag-Cp samples did not contain products of spontaneous partial proteolytic degradation, characteristic of holo-Cp samples. Fractions of Ag-Cp and holo-Cp (from blood serum of control rats) were compared by optical spectra, tertiary structure, susceptibility to thermal denaturation, and by atomic Cu and Ag content. Ag-Cp contained 1-2% Cp, which is similar by spectral and catalytic properties with holo-Cp. [Ag]:[Cu] ration in Ag-Cp samples was about 4:1. As evidenced by circular dichroism and differential scanning calorimetric studies, the major apo-fraction of Ag-Cp lacked tertiary structure of native Cp and was significantly misfolded, which might explain its resistance to spontaneous partial proteolytic degradation.

[Dynamics of the formation of secondary reproductive structures in Streptomyces zone-forming colonies as determined from confocal microscopy data].

The dynamics of the formation of secondary structures on the colony surface, so-called air mycelium concentric rings, was investigated by confocal microscopy and using Streptomyces zone-forming colonies as a model of a self-organizing system. The occurrence of luminescence in reproductive structures was registered, whereas in vegetative structures it was almost completely absent. It was shown that secondary reproductive structures begin to form within the thickness of substratum mycelium as branches or as an apical extension of vegetative gyphes, followed by the formation of numerous secondary branches filled with protospores.

[Dynamic of the substrate mycelium growth unit in streptomyces colonies].

The regularities of changes in the length of the substrate mycelium growth unit of a developing streptomyces colony have been studied. The parameters of the dependence of this process on the age of the colony, the type of the limiting substrate, and its concentration in nutrient medium have been established.

Reviving an old idea: can artificial pneumothorax play a role in the modern management of tuberculosis?

OBJECTIVE: To determine the usefulness of artificial pneumothorax (AP) in the management of pulmonary tuberculosis (PTB) patients when anti-tuberculosis treatment is ineffective. DESIGN: We evaluated the outcome of therapy in 214 patients with cavitary PTB bacteriologically confirmed by culture treated during 1998-2004, 78.9% of whom had multidrug resistance. AP was applied in 109 patients (56 newly diagnosed TB and 53 retreatment cases). A control group consisted of 105 patients (respectively 55 and 50) treated without AP. The average period of AP application was 4.5 months for newly diagnosed patients and 9 months in retreatment cases. Anti-tuberculosis treatment regimens in both groups were based on drug susceptibility test results. RESULTS: Culture negativity was achieved in patients treated with AP in all new cases and in 81.1% of retreatment cases. Cavity closure occurred in 94.6% and 67.9% respectively. In the control group, culture negativity was achieved in respectively 70.9% and 40.0%, and cavity closure occurred in respectively 56.3% and 24.0%. CONCLUSION: AP considerably improved the treatment outcome in both newly diagnosed and retreatment patients. This procedure can be considered a useful addition in managing certain patients with cavitary TB, particularly those with drug resistance.

[Artificial pneumothorax in the treatment of destructive pulmonary tuberculosis complicated by its drug-resistant pathogen].

A hundred and nine patients with complicated destructive pulmonary tuberculosis who had received chemotherapy with reserve drugs, artificial pneumothorax (AP), pneumoperitoneum (PN), physiotherapy, and resection surgery were followed up. The application of video thoracoscopy made it possible to eliminate any types of pleural adhesions. Individualization of therapeutic measures considerably increases the efficiency of treatment. AP is the method of choice in therapy of newly detected patients who have undergone ineffective routine treatment regimens.

[Spontaneous sector formation in soil streptomycetes colonies]. / Spontannoe sektorooobrazovanie v koloniiakh pochvennogo streptomitseta.

A model of the formation of sectors during the growth and zone formation of a colony of the soil radiant fungus streptomycetes was developed. It was shown that the basic parameters determining the shape of the sector border are the correlations between the growth rates of the sector of mycelium hyphae and the remainder of the colony and between the frequency and the numbers of branching order of these hyphae. Based on the long-standing observations, a polyseasonal dependence of spontaneous sector formation in streptomycetes zone-forming colonies was demonstrated.

[Affection of the central nervous system in Wegener's granulomatosis]. / Porazhenie tsentral'noi nervnoi sistemy pri granulematoze Vegenera.

A case of a lesion of the central nervous system in Wegener's granulomatosis with neuritis of craniocerebral nerves, granulomas, vasculitis and foci of ishemic necrosis and hemorrhages in the brain tissue is reported. Diagnosis of Wegener's granulomatosis in a female aged 48 years was confirmed morphologically and by detection of specific antibodies. In spite of prednisolone (20 mg/day) and cyclophosphamide treatment (200 mg per week), hemiplegia, aphasia appeared which progressed and resulted in a death of the patient. Histologically lesions in many organs were found: middle ear, lungs, kidneys, brain, destructive vasculitis, necrotic foci and polymorphic lung granulomas, fibrosing alveolitis, polymorphocellular granulomas, multiple infarctions in the kidneys, endothrombovasculitis, necrotic foci and granulomas with glial reaction in the brain tissue.